1. Field of the Invention
This invention relates to "wind" vanes which are mounted on the fuselage of an aircraft for such purposes as sensing the angle of attack of an aircraft and more particularly to such a vane which is constructed so that when struck by a flying object and broken, it will be retained to the aircraft fuselage and will tend not to shatter.
2. Description of the Related Art
Wind vanes are commonly mounted on the fuselages of aircraft to measure such parameters as the angle of attack of the aircraft. In its protruding position in the airstream, such vanes are subject to being struck by birds and other objects. If such a vane is struck by sufficient force to cause it to shatter or break off, it presents the hazzard of entering the engine or striking against parts along the fuselage which could cause the engine to fail or cause other serious damage. A particular problem is presented in this regard in that such vanes are generally mounted near the nose of the aircraft from where there is a stronger risk of a broken off vane entering the engine. No prior art aircraft vane constructions for obviating this problem are known to applicant. While involved in an unrelated art, the problem presented when highway posts are struck by vehicles and fly into oncoming traffic is at least somewhat analogous in nature. This problem is recognized in U.S. Pat. No. 3,912,404 to Herbert L. Katt and U.S. Pat. No. 4,071,970 to Richard A. Strizki. In Katt, a highway post is described in which a frangible coupling is employed such that on impact, the frangible coupling is broken and a tie strip prevents the broken off post sections from flying loose. In Strizki, a highway post is made with a weakened line portion which operates in conjunction with a hinge such that when struck, the post will break off at the weakened portion yet is retained to its base portion by the hinge. There is no suggestion in either of these references of an aircraft angle of attack vane which is constructed so that it will not fly free of the aircraft fuselage or shatter under high impact.